Wireless receiving circuits



Oct. l5, 1929. E. w. ENGLE ETAL 197329041 WIRELESS RECEIVING CIRCUITS Filed Dec. 28, 1925 mak f-s.

Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE y EDGAR W. ENGLE, F FOREST, AND HAROLD L. OLESEN, OF HIGHLAND PARK, ILLINOIS, ASSIGNORS TO FANSTEEL PRODUCTS COMPANY, INC., OF NORTH CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK WIRELESS RECEIVING CIRCUITS Application led December 28, 1923. Serial No. 683,172.

This invention relates to receiving equipment for wireless telephone circuits, and particularlypto means whereby the current necessary to operatea receiving set employing an audion bulb may be obtained from an alternating current line as the ordinary lighting system power line.

'lhe object of the invention is to provide rectifying means, and means Vfor smoothing out the current pulsations such that no pulsa-v tions or variations of current will be noticeable in the receiving set.

Referring to t-he drawing which schematically shows one form of applicants invention, indicates the core of a transformer, the primary coil 11 of which is bridged across the conductors 12 of an alternating current lighting system. The current on the conductors 12 may be of any desired voltage, but in the present disclosure the values of the various elements shown were employed where the line voltage was/approximately 110 volts.

Associated with the core 10 is a secondary coil 13 in series with the conductors 14 and The coil 13 is such that a current of approximately 110 volts is set up in the conductors 14 and 15. In certain types of receiving circuits, the coil 13 need not be employed and the conductors 14 and 15 may be joined directly to the conductors 12. In other types of receiving circuits, however, the ground which is commonly present on one or the other of the power circuit conductors has an injurious effect on the operation of the receiving equipment, and in such systems it is desirable to join the conductors 14 and 15 to the power line through a transformer.

Also associated with the core 10 is a secondary transformer coil 16 which is in series with the conductors 17 arid 18. Secondary 16 is so proportioned to the primary 11 as to give an output current in the neighborhood of 180 volts. If desired, instead of associating the secondary coils 13 and 16 with the primary coil 11, separate and distinct transformers may be employed.

Arranged in series in the conductor 14 is a plurality of rectiicrs 19, preferably of the type employing a tantalum electrode in an acid electrolyte. The last rectifier 19 is one inch square core 27 with a small air gap 28, say of approximately f. It is not necessary, however, that 'these exact dimensions be employed.

Bridged between the conductors and 21 is a condenser 29, and bridged between the conductors 26 and 21 is a condenser 30. Satisfactory results have been obtained by employing at 29 a .condenser of approximately 6 `microfarad capacity, and at30 a condenser of approximately 12 microfarad capacity. Conductor 17 extends to one element Jof the adjustable resistance:31, a 'rectifier 32 of the same character as those indicated at 19 being included in the circuit. Conductor 18 is joined to the other element of the adjustable resistance 31 through the filament 33 of the audion and the coil 34. Satisfactory results have been obtained by employing at 34 a coil comprising in the neighborhood of- 1500 turns of No. 22 wire on a three inch square core.

Bridged between the conductors 17 and 18 on one side ofthe coil 34 is a condenser 35, and bridged between the conductors 17 and 18 on the'other side of the coil 34 is a con'- denser 36. Good results have been obtained by using an Smicrofarad condenser at 35, and a 4 microfarad condenser at 36.

In connection with wireless circuits, it is often desirable to have a third source of eurrent known as the C battery. Inreceiving equipment, this C battery obviates the use of the grid leak and is often found very` desirable.

At the left-in the drawing is shown a means for supplying the C battery current which, in the present disclosure, renders the grid leak unnecessary. At 48 and 49 are shown two secondaries which, if desired, may be `-considered the halves of a single secondary associated with the core 10. The potential across each of these secondaries is about 10 volts. The remote ends ofthe secondary 48--49 are joined by the conductors 50 and 51 to the rectiiers 52 and 53, which are of the same character as those previously described. The mid point of the coil 48-49 isfjoined by the conductor 55 to the im edance 54 which prefer ably has a value o approximately 48 to 50 henries, the opposite side of the impedance being joined by the conductor 5.6 to one end of the resistance 57.. The o posite end of the resistance 57 is joined' to tlie output side of the rectiier 53 by means of the conductor 58. The output side of the rectifier 52 is joined to conductor 58 by the conductor 59. The conductor 58 is extended beyond the resistance 57 and terminates at ground 25. Associated with the resistance 57 is a movable contact 60 which is joined by the conductor 61 to one terminal orf the inductance coil 41, the other terminal of which is joined to a terminal of the variometer 38, the other terminal of the variometer being joined to the antenna 37 by the conductor 39, a condenser 40 being interposed in said conductor. The grid 42 of the electronic detector is joined to the conductor 39 by the conductor 43.

As previously explained, the conductor 21 terminates in one terminal of the variometer 20, the other terminal of the variometer 20 being 'oined to the plate 46 by the conductor 47. T e condensers 62 and 63 are preferably arranged to have aca acity of about 4 microfarads and six micro arads, res ectively.

Although but a single type o wireless circuit is shown in the present drawings and above described, it is to be understood that the current supplying arrangement of the present invention may be utilized with wireless circuits of ractically every character and will give uni ormly good results, it being necessary only to alter the values of the va' rions elements such as the secondaries, condensers, and impedance coils. Also, where` a high voltage'and large output is required, it is necessar to include a number of rectifier cells in series, in accordance with lthe voltage and amperage of the current required.

While certain values of condensers and inductance coils have been indicated in connection with the above circuit, it is to be understood that these values may be departed from to a certain extent and still obtain very good results. However, employing equipment such as indicated above, the quality of the messages received is found to be good both in volume and in freedom from the undulatory effects which have heretofore been noticeable when an attempt has been made to derive the current for the operation of vacuum tube receiving sets from an alternating current source.

As the operation of receiving circuits of the kind herein disclosed, when supplied with current from a. direct current source, is well known, it is believed that a description of the operation will be superfluous, as the current supplied to the receiving set by the rectifying and smoothing lequipment'. herein disclosed has, in eiect, substantially all the characteristics of direct current.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. A power source for radio equipment, including a transformer provided with three secondary circuits wound on'the same core, rectifier means in each secondary circuit, an impedance in each secondary circuit, a capacity unit across the line on each side of each im edance, a plate connection in one circuit, a lament connection in another circuit, a grid connection in a third circuit, and a low resistance non-inductive connection from each of said circuits to a common point whereby the residual pulsations of the current in the various tube elements 'are synchronized.

2. A power supply unit for radio equipment, including transformer means provided with three secondary circuits, rectifier and filter means in each secondary circuit, a plate connection in one circuit, a filament connection in another circuit, a grid connection in a third circuit, and a connection from each circuit to a ground potential.

In witness whereof, we hereunto subscribe our names this 26th day of October, 1923.

EDGAR W. ENGLE. HAROLD L. OLESEN. 

